It is not uncommon to see Bijou recipes with equal parts gin, Chartreuse and sweet vermouth, as called for in Harry Johnson's Bartender's Manual. In fact...
Yep, very very good. The extra vermouth seems to bring out the herbal fruitiness of the chartreuse and the dryness of the (four pillars) gin even more. Very delicious. I find I need to be super cautious with the built in dropper otherwise it completely overwhelms the other elements.
On a tangent, I just got a (heavily discounted) bottle of monkey 47 for the first time. Any recommendations for cocktails that would particularly suit?